Device for wavelength combining of laser beams

Patent metadata

Field	Value
Publication number	US-9690107-B2
Application number	US-201313833974-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Mar 15, 2013
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

A device for wavelength coupling of laser beams ( 2 a, . . . 2 n ) with different wavelengths (λ 1 , . . . λ n ), comprising: at least one laser source for generating a plurality of laser beams ( 2 a, . . . , 2 n ), and an overlapping device for spatial overlapping of the plurality of laser beams ( 2 a, . . . , 2 n ) for forming an overlapped laser beam with a plurality of wavelengths (λ 1 . . . λ n ). The device has a feedback device arranged between the laser source and the overlapping device for feeding a radiation proportion of the laser beams ( 2 a, . . . , 2 n ) to be overlapped back to the laser source, the feedback device comprising a partially reflecting angle-dispersive optical element, in particular a partially reflecting diffraction grating. The overlapping device may, for example, be configured as a transmitting or reflecting diffraction grating whose optical properties are adapted to the optical properties of the partially reflecting diffraction grating to overlap the laser beams ( 2 a, . . . , 2 n ) in an essentially dispersion-free manner.

First claim

What is claimed is:

1. A device for wavelength coupling of laser beams ( 2 a , . . . , 2 n ) with different wavelengths (λ 1 , . . . , λ n ), comprising:
at least one laser source for generating a plurality of laser beams ( 2 a , . . . , 2 n );
an overlapping device for spatial overlapping of the plurality of laser beams ( 2 a , . . . , 2 n ) for forming an overlapped laser beam with a plurality of the different wavelengths (λ 1 , . . . , λ n );
a feedback device arranged in a path of the overlapped laser beam for feeding a radiation proportion of the overlapped laser beam back to the laser source; and
a phase correction device for phase correction of the radiation proportion reflected back to the laser source,
wherein the feedback device is configured as an output coupling element with a surface partially reflecting the overlapped laser beam, and wherein the partially reflecting surface of the output coupling element has a curvature for the phase correction of the radiation proportion reflected back to the laser source.

2. The device according to claim 1 , further comprising:
a feedback device arranged in a beam path between the laser source ( 3 ) and the overlapping device for feeding a radiation proportion of the laser beams to be overlapped ( 2 a , . . . , 2 n ) back to the laser source,
the feedback device comprising a partially reflecting angle-dispersive optical element.

3. The device according to claim 2 , further comprising: at least one imaging optical element arranged between the laser source and the partially reflecting angle-dispersive optical element for the spatial overlapping of the laser beams ( 2 a , . . . , 2 n ) of the laser source on the partially reflecting angle-dispersive optical element.

4. The device according to claim 2 , wherein the partially reflecting diffraction grating is arranged at the Littrow angle (α L1 , . . . , α Ln ) to the striking laser beams ( 2 a , . . . , 2 n ).

5. The device according to claim 2 , wherein the partially reflecting angle-dispersive optical element comprises a partially reflecting diffraction grating.

6. The device according to claim 1 , wherein the overlapping device comprises a diffraction grating.

7. The device according to claim 6 , wherein a grating constant (g 1 ) of the partially reflecting diffraction grating of the feedback device and a grating constant (g 2 ) of the diffraction grating of the overlapping device are matched to each other so that the overlapped laser beam leaves the diffraction grating of the overlapping device at essentially the same emergent angle (β).

8. The device according to claim 7 , wherein the diffraction grating of the feedback device and the diffraction grating of the overlapping device are aligned parallel with each other and the overlapped laser beam leaves the diffraction grating of the overlapping device at an emergent angle (β) of essentially 0°.

9. The device according to claim 7 , wherein the following applies to the grating constant g 2 of the diffraction grating of the overlapping device and to the grating constant g 1 of the partially reflecting diffraction grating of the feedback device: m 2 /g 2 =m 1 /2 g 1 wherein m 2 denotes a diffraction order of the diffraction grating of the overlapping device and m 1 denotes a diffraction order of the partially reflecting diffraction grating of the feedback device.

10. The device according to claim 7 , wherein the partially reflecting diffraction grating of the feedback device and the diffraction grating of the overlapping device are designed as a common optical element.

11. The device according to claim 7 , wherein a beam telescope is arranged between the partially reflecting diffraction grating of the feedback device and the diffraction grating of the overlapping device.

12. The device according to claim 11 , wherein the following applies to the grating constant g 2 of the diffraction grating of the overlapping device and the grating constant g 2 of the partially reflecting diffraction grating of the feedback device: A m 2 /g 2 =m 1 /(2 g 1 ), where m 1 denotes a diffraction order of the partially reflecting diffraction grating of the feedback device, m 2 denotes a diffraction order of the diffraction grating of the overlapping device and A denotes an imaging ratio of the beam telescope.

13. The device according to claim 1 , wherein the overlapping device is configured as a diffraction grating which is rotatably mounted about an axis of rotation for altering the wavelengths (λ 1 . . . , λ n ) of the laser beams ( 2 a , . . . , 2 n ) to be overlapped.

14. The device according to claim 1 , wherein a polarisation filter is arranged between the light source and the feedback device.

15. The device according to claim 14 , wherein the polarisation filter and the overlapping device or the polarisation filter and the feedback device are configured as a common optical element.

16. The device according to claim 14 , wherein the polarisation filter is arranged in a beam path between the overlapping device and the feedback device.

17. The device according to claim 1 , wherein a phase correction element of the phase correction device and the feedback device are configured as a common optical element.

18. The device according to claim 1 , wherein the output coupling element is configured for beam forming the outcoupled overlapped laser beam.

19. The device according to claim 1 , wherein the phase correction device has an imaging optical element for the collimation of the overlapped laser beam to the partially reflecting, flat surface of the output coupling element, wherein the radius of curvature (R K ) of the imaging optical element is adapted to the radius (R p ) of the phase curvature of the overlapped laser beam.

20. The device according to claim 1 , wherein the overlapping device and the feedback device are configured as a common optical element.

21. The device according to claim 20 , wherein the overlapping device and the output coupling element are configured as the common, optical element.

22. The device according to claim 1 , further comprising:
a first imaging optical element arranged in the beam path between the laser source and the overlapping device, which element, together with a second imaging optical element arranged in the beam path between the laser source and the overlapping device, forms a beam telescope.

23. The device according to claim 1 , further comprising:
an imaging optical element arranged in the beam path between the laser source and the overlapping device, which element, together with an imaging optical element arranged in the beam path of the overlapped laser beam, forms a beam telescope.

24. The device according to claim 1 , further comprising:
a beam deflection device for aligning the laser beams ( 2 a , . . . , 2 n ) to be overlapped to a common overlapping area of the overlapping device or of the feedback device.

25. The device according to claim 24 , wherein the beam deflection device has at least one facet element with a plurality of facets for aligning a respective laser beam ( 2 a , . . . , 2 n ) to the common overlapping area.

26. The device according to claim 24 , wherein the beam deflection device has a plurality of deflection mirrors ( 22 a , . . . , 22 n ) for aligning the laser beams ( 2 a , . . . , 2 n ) to the common overlapping area.

Assignees

• Trumpf Laser Gmbh

Inventors

• Negoita Viorel C
• Vethake Thilo
• Killi Alexander
• Tillkorn Christoph
• Strohmaier Stephan
• Ried Steffen
• Li Yufeng
• An Haiyan
• Barnowski Tobias

Classifications

• H01S3/1307

  Stabilisation of the phase · CPC title

• G02B27/286

  for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another (G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34) · CPC title

• H01S5/4012

  Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms · CPC title

• G02B27/1006 Primary

  for splitting or combining different wavelengths (G02B27/1086, G02B27/141 take precedence) · CPC title

• G02B27/4277

  being separated by an air space · CPC title